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Chub Mackerel fish identification, its habitats, characteristics, fishing methods.
The chub mackerel is a small member of the Scombridae family growing to a length of about 8 to 14 inches is widespred in the Atlantic, Indian, and Pacific Oceans, commercially cultured in Japan and used in Chinese medicine. It is a good food fish and is marketed in many different ways. Found in the Atlantic, Indian, and Pacific Oceans, chub mackerel occur in warm and temperate transition waters and adjacent seas from Alaska to California, from the Gulf of St. Lawrence to the Florida Keys and Cuba, and also from Venezuela to southern Brazil.
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The chub mackerel, Scomber japonicus, also known as the Pacific mackerel, Blue mackerel, common mackerel, tinker mack-erel, Japanese mackerel, Spanish mackerel, Scomber, Smaach and sometimes referred to as a "hardhead" or "bullseye", closely resembles the Atlantic chub mackerel. In the eastern Pacific, they occur from Alaska to Cabo San Lucas and are most abundant between Monterey, California, and southern Baja California. In the western Atlantic, they extend from the Gulf of St. Lawrence to the Florida Keys and Cuba, and also from Venezuela to southern Brazil. Chub mackerel are apparently absent from Indonesia and Australia.
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Description
The chub mackerel have fusiform and elongate body, slightly compressed laterally, depth 1/4th to 1/5th of a length, with a sharp muzzle. Head is 1/3rd of a length, eye is 1/3rd to 1/4th in a head, snout 1/3rd, maxillary is 1/2nd to 1/3rd, interorbital is 1/5th. Inter-pelvic process (a single small flap) between pelvic fins is small and single. Swim bladder is present. First haemal spine is posterior to first inter-neural process and 12 to 15 inter-neural bones under first dorsal fin. Spinous dorsal are high, third dorsal spine highest, 1/3rd in head. Anal fin spine conspicuous clearly separated from anal rays but joined to them by a membrane. Back with narrow stripes which zigzag and undulate.
Gil rakers are long and slender; each gill raker is armed with long slender teeth. Caudal peduncle usually has 5 finlets on the upper and lower edge behind the dorsal and anal fins. Two small keels are on each side of caudal peduncle (at base of caudal-fin lobes), but no central keel between them. The first and second dorsal fins have a large space between them, shorter than or equal to the first dorsal fin base. Lateral line not interrupted and caudal fin forked. The entire body is scaled. Scales behind head and around pectoral fins are larger and more conspicuous than those covering rest of body, but no well-developed corselet.
Distinguishing characteristics: Body elongate and rounded, snout is pointed, caudal peduncle slim. Front and hind margins of eye covered by adipose eyelids. Two widely separated dorsal fins (interspace is shorter than or equal to the length of first dorsal-fin base), the first with 9 to 11 spines; 5 dorsal and 5 anal finlets. Swim bladder present. They color is back steel-blue crossed by faint wavy lines; lower sides and belly silvery-yellow with numerous dusky rounded blotches.
9-11 Dorsal spines with 11-12 soft rays
Anal spine with 12–14 soft rays
Vertebrae: 31
12-15 inter-neural bones under first dorsal fin
5 finlets on the upper and lower edge on caudal peduncle
Max. Length 25 in (64 cm), commonly to 30 cm
Max. Weight 4.75 lbs (2.5 kg.)
Max. Age of 16 years
The chub mackerel has a bluish or greenish back with roughly 25 to 30 irregular dark-blue to black bars that dissolve into a series of dusky spots extending down to middle of side near the lateral line. The pectoral fin has a black spot. Belly is pale silvery unmarked (Pacific) or with wavy lines (Atlantic). Dorsal is green and yellow, with thin blue to black lines.
The chub mackerel is similar to the frigate mackerel, which also has 30 irregular bars on its back, except that it has scales all over its body; the frigate has scales only in corselets around the pectoral fins. The chub mackerel closely resembles the Atlantic chub mackerel. Most important of the differences, anatomically, is the fact that the hardhead has a well-developed swim bladder attached with the esophagus, which the "true mackerels" in the Scomber genus lack. The Atlantic chub mackerel is silvery-sided below the mid line, whereas the lower part of the sides of the hardhead (otherwise colored similar to Atlantic) are mottled with small dusky blotches, and the chub has a larger eye than the Atlantic. Less obvious differences are that the dorsal fins are closer together in the chub and that there are only 9 or 10 spines in its first dorsal fin instead of 11 or more, which is the usual count in the Atlantic mackerel.
Habitats
Chub mackerel is a coastal pelagic species with gregarious behavior, inhabit inshore and offshore waters at the surface, schooling by size in the company of other species of fish, including small Bluefin tuna, Sarda chiliensis, Trachurus symmetricus and Sardinops sagax, bonitos, jacks, and clupeids. Huge schools sweep along the eastern Pacific coast in the summer and fall. In the western Pacific, chub mackerel move into deeper areas of Asian waters to remain inactive during the winter season. Adults stay near the bottom during the day; go up to the open water at night, where they feed on copepods and other crustaceans, fishes and squids.
Chub mackerel feeding habits are much the same as Atlantic mackerel, they feed on the same species of pelagic crustaceans and Sagittae, copepods, amphipods, salpae, appendicularians, and squid, as well as on small pelagic fishes such as anchovy, pilchard, sardinella, sprat, silversides, young herring, and also pelagic invertebrates. It feeds on zooplankton and mackerel fry other small fish.
Spawning:
Chub mackerel, Scomber japonicus, spawn in batches, more than once per season, from spring through summer, from March to October, with peak spawning in June, with more northerly fish spawning later in the season. Most of males and females reach sexual maturity at the age of 2 and length 18 cm. All males and females are sexually mature at age 4 and length 20.4 cm and 16.8 cm, respectively. The overall sex ratio is approximately 0.68 with females significantly predominant. The average female from April through July spawned 8-16 times during the 101-day spawning period with 1-5 days average interval between spawns.
They spawn in areas with substantial biological production, to ensure adequate adult and larval feeding. The water temperature, 15–20 C, is one of the main triggers of spawning activities in chub mackerel. They spawn near the surface and the eggs float in the water column. The number of eggs produces during spawning period increases with age and size, with an individual female spawning produce 550,000 - 1,000,000 pelagic eggs per season. Eggs and larvae are pelagic.
Chub mackerel are generally caught at night, with surrounding nets that surround the schools attracted towards the surface by the lampara lamp light. It can also be caught using drift nets, bottom trawls or midwater drifting trawls, with purse seines, often together with sardines, and sometimes using light trolling lines, gill nets, traps and beach seines. It can be caught all year round, but especially from June to November. They follow thrown bait as readily and bite quite as greedily as Atlantic mackerel.
The chub mackerel’s meat is high in protein. Its fat is high in omega-3 fatty acids, which form 26% of its total fatty acids. Chub mackerel flesh are rich in vitamins A, B1, C and D. Marketed fresh, frozen, smoked, salted, and occasionally also canned. It is delicious filleted and served raw, simply marinated in oil, lemon, salt and pepper. Eaten fried, broiled and baked. The chub mackerel ia commercially cultured in Japan and used in Chinese medicine.
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